GALVESTON — A Galveston man filed a federal lawsuit Tuesday challenging a provision of the Texas Constitution defining marriage as a union of a man and a woman.

Domenico Nuckols, 60, said he believes that he will prevail because of last week's U.S. Supreme Court ruling striking down the federal Defense of Marriage Act, which included the same definition of marriage.

“It's going to be an uphill battle, but I fired the first shot,” Nuckols said.

The same-sex rights group Equality Texas was unaware of any similar lawsuits since the court decision, said Chuck Smith, executive director. A section of the state Constitution's Bill of Rights reads, “Marriage in this state shall consist only of the union of one man and woman.”

A ballot measure adding the clause passed in 2005 with 75 percent of the vote.

Lambda Legal, the national same-sex rights legal organization, did not respond to a request for comment.

The office of Texas Attorney General Greg Abbott, who is named in the lawsuit along with Gov. Rick Perry, declined comment, but Abbott's office has opposed same-sex marriage in other cases.

Nuckols, a retired nuclear engineer, is representing himself and has asked the court to waive his filing fees.

Although supportive of Nuckols' goal, Smith worried that Nuckols' lack of an attorney may indicate that he doesn't have a well-planned legal strategy.

“I would not encourage someone to do something like this without having legal counsel to assess the strategic values of the case,” Smith said. “If you don't do it the right way, you can do more harm than good by losing a case and setting a negative precedent.”

Yet successful lawsuits have been brought without an attorney, most notably by Clarence Earl Gideon, a convicted felon with an eighth-grade education who filed a lawsuit from jail that ended in a landmark Supreme Court decision in 1963 establishing the right to legal counsel.

Smith said he expected similar lawsuits to be filed.

“There are so many, many people affected by what the restrictions are in Texas, I think it is inevitable that there will be lawsuits filed,” he said.

Nuckols said he was inspired to file his lawsuit by last week's court decision and the deportation of his gay partner in 1986. He believes that his partner would not have been deported had the laws then allowed them to marry.

He met Wha Sing Lee, now 60 and living in Malaysia, in Taiwan while working for a company building a nuclear power plant there.

“Maybe you are lucky to meet somebody once or twice where all the pieces fit together,” Nuckols said.

Lee entered the United States legally and was attending Emporia State University, in Emporia, Kan., when he was deported. Nuckols moved to Galveston soon after and has lived in Texas since then.

“I want to make it possible for anybody in this state to live a happy and productive life,” he said.